Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in
the exchange of trace gases and aerosols between the earth’s surface and the atmosphere. The gases
covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O3, CH4, N2O and particles in the size
range 1 nm–10 mmincluding organic and inorganic chemical species. The main focus of the reviewis on the
exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some
new developments in ocean–atmosphere exchange are included. The material presented is biased towards
the last decade, but includes earlier work, where more recent developments are limited or absent.
New methodologies and instrumentation have enabled, if not driven technical advances in measurement.
These developments have advanced the process understanding and upscaling of fluxes, especially
for particles, VOC and NH3. Examples of these applications include mass spectrometric methods, such as
Aerosol Mass Spectrometry (AMS) adapted for field measurement of atmosphere–surface fluxes using
micrometeorological methods for chemically resolved aerosols. Also briefly described are some advances
in theory and techniques in micrometeorology.
For some of the compounds there have been paradigm shifts in approach and application of both techniques
and assessment. These include flux measurements over marine surfaces and urban areas using
micrometeorological methods and the up-scaling of flux measurements using aircraft and satellite remote
sensing. The application of a flux-based approach in assessment of O3 effects on vegetation at regional scales
is an important policy linked development secured through improved quantification of fluxes. The coupling
of monitoring, modelling and intensive flux measurement at a continental scale within the NitroEurope
network represents a quantum development in the application of research teams to address the underpinning
science of reactive nitrogen in the cycling between ecosystems and the atmosphere in Europe.
Some important developments of the science have been applied to assist in addressing policy questions,
which have been the main driver of the research agenda, while other developments in understanding have
not been applied to their wider field especially in chemistry-transport models through deficiencies in
obtaining appropriate data to enable application or inertia within the modelling community. The paper
identifies applications, gaps and research questions that have remained intractable at least since 2000
within the specialized sections of the paper, and where possible these have been focussed on research
questions for the coming decade.
- biogenic emissions
- compensation points
- dry deposition
- trace gas fluxes